Known examples of valve elements used in valves referred to as a bellows valve and a lift valve include a valve element including a disc-shaped abutting member formed of a synthetic resin configured to close a path opening by coming into abutment with a path opening edge, and a holding member having a recessed portion into which the abutting member is fitted, in which the holding member is caulked and thus the abutting member is held by the holding member (Patent Literature 1).
In such a valve element, when the valve is subjected to a temperature cycle (repetition of high temperature→low temperature→high temperature), the abutting member formed of a synthetic resin repeats relatively large expansion and contraction. Therefore, a pressing force that the abutting member applies to the holding member repeats pressurization when expanded and decompression when contracted, so that a force of a peripheral wall that forms a recessed portion of the holding member to press the abutting member is reduced, and hence a gap is formed between the holding member and the abutting member, which may cause a state in which the abutting member is rotatable (slidable) with respect to the holding member.
When the abutting member is allowed to rotate, problems such as lowering of sealing properties due to rotation or particles generated by the sliding motion occurring at the time of relative rotation may arise, and in some cases, the abutting member may drop off from the holding member.